ARM: 9426/1: vfp: Move sending signals outside of vfp_state_hold()ed section.

VFP_bounce() is invoked from within vfp_support_entry() and may send a
signal. Sending a signal uses spinlock_t which becomes a sleeping lock
on PREEMPT_RT and must not be acquired within a preempt-disabled
section.

Move the vfp_raise_sigfpe() block outside of the vfp_state_hold() section.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 28dafae..d44867f 100644 (file)
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -268,7 +268,7 @@ static void vfp_panic(char *reason, u32 inst)
 /*
  * Process bitmask of exception conditions.
  */
-static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_regs *regs)
+static int vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr)
 {
        int si_code = 0;
 
@@ -276,8 +276,7 @@ static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_
 
        if (exceptions == VFP_EXCEPTION_ERROR) {
                vfp_panic("unhandled bounce", inst);
-               vfp_raise_sigfpe(FPE_FLTINV, regs);
-               return;
+               return FPE_FLTINV;
        }
 
        /*
@@ -305,8 +304,7 @@ static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_
        RAISE(FPSCR_OFC, FPSCR_OFE, FPE_FLTOVF);
        RAISE(FPSCR_IOC, FPSCR_IOE, FPE_FLTINV);
 
-       if (si_code)
-               vfp_raise_sigfpe(si_code, regs);
+       return si_code;
 }
 
 /*
@@ -352,6 +350,8 @@ static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs)
 static void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
 {
        u32 fpscr, orig_fpscr, fpsid, exceptions;
+       int si_code2 = 0;
+       int si_code = 0;
 
        pr_debug("VFP: bounce: trigger %08x fpexc %08x\n", trigger, fpexc);
 
@@ -397,8 +397,8 @@ static void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
                 * unallocated VFP instruction but with FPSCR.IXE set and not
                 * on VFP subarch 1.
                 */
-                vfp_raise_exceptions(VFP_EXCEPTION_ERROR, trigger, fpscr, regs);
-               return;
+               si_code = vfp_raise_exceptions(VFP_EXCEPTION_ERROR, trigger, fpscr);
+               goto exit;
        }
 
        /*
@@ -422,14 +422,14 @@ static void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
         */
        exceptions = vfp_emulate_instruction(trigger, fpscr, regs);
        if (exceptions)
-               vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs);
+               si_code2 = vfp_raise_exceptions(exceptions, trigger, orig_fpscr);
 
        /*
         * If there isn't a second FP instruction, exit now. Note that
         * the FPEXC.FP2V bit is valid only if FPEXC.EX is 1.
         */
        if ((fpexc & (FPEXC_EX | FPEXC_FP2V)) != (FPEXC_EX | FPEXC_FP2V))
-               return;
+               goto exit;
 
        /*
         * The barrier() here prevents fpinst2 being read
@@ -441,7 +441,13 @@ static void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
  emulate:
        exceptions = vfp_emulate_instruction(trigger, orig_fpscr, regs);
        if (exceptions)
-               vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs);
+               si_code = vfp_raise_exceptions(exceptions, trigger, orig_fpscr);
+exit:
+       vfp_state_release();
+       if (si_code2)
+               vfp_raise_sigfpe(si_code2, regs);
+       if (si_code)
+               vfp_raise_sigfpe(si_code, regs);
 }
 
 static void vfp_enable(void *unused)
@@ -773,6 +779,7 @@ static int vfp_support_entry(struct pt_regs *regs, u32 trigger)
                 * replay the instruction that trapped.
                 */
                fmxr(FPEXC, fpexc);
+               vfp_state_release();
        } else {
                /* Check for synchronous or asynchronous exceptions */
                if (!(fpexc & (FPEXC_EX | FPEXC_DEX))) {
@@ -794,10 +801,10 @@ static int vfp_support_entry(struct pt_regs *regs, u32 trigger)
                        }
                }
 bounce:                regs->ARM_pc += 4;
+               /* VFP_bounce() will invoke vfp_state_release() */
                VFP_bounce(trigger, fpexc, regs);
        }
 
-       vfp_state_release();
        return 0;
 }